Carry-save-adder (CSA) is the most often used type of operation in implementing a fast computation of arithmetics of register-transfer-level design in industry, This paper establishes a relationship between the properties of arithmetic computations and several optimizing transformations using CSA's to derive consistently better qualities of results than those of manual implementations. In particular, we: introduce two important concepts, operation duplication and operation split, which are the main driving techniques of our algorithm for achieving an extensive utilization of CSA's, Experimental results from a set of typical arithmetic computations found in industry designs indicate that automating CSA optimization with our algorithm produces designs with up to 54% faster timing and up to 42% smaller area.